Low Water Cut Off Keeps Tripping [7 Easy Solutions]

Low water cut off keeps tripping due to the malfunctioning LWCO, faulty ground, the boiler requires skimming, oils on the LWCO probe, low water condition, water-logged float, and defective sensor.

Any of these factors can create issues in your boiler’s LWCO device, and it can start tripping. 

low water cut off keeps tripping

We conducted in-depth research on these factors and explained the detailed causes and solutions below. So, read this article sharply, and you will undeniably learn to fix your LWCO’s tripping trouble by yourself. 

What is Low Water Cut Off

Low water cut off is a float switch or mechanical device that is used to shut off the boiler’s fuel or close up the burner. After a certain point of water drops, the boiler runs. This low water cut-off switch prevents its running.

The boiler can suffer from catastrophic failure or rupture when it burns without water. The low water cut-off prevents the boiler’s dry-fried situation. 

Low Water Cut Off Keeps Tripping [7 Easy Solutions]

Normally your boiler’s LWCO device functions well, and it is very reliable. But the following factors can cause the tripping or breakdown of this device. We explained the detailed causes and solutions of each factor. Lest start: 

Note: You can also read how to fix no water in the Boiler Sight Glass.

1. Defective LWCO (Low Water Cut Off)

The malfunctioning LWCO is the prime reason why your low water cut-off keeps tripping. When the unit itself goes bad, it fails to function properly.

And it fails to prevent the boiler’s catastrophic failure situation. As a result, the LWCO starts tripping. The concerning factors causing this issue are: 

  • Incorrect maintenance or lack of proper maintenance 
  • Improper modification 
  • Physically damaged LWCO
  • Short cycling 
  • Bad plugged gauge glass 
  • Defective probe lead wire 


If you see your LWCO starts tripping, check this device first to ensure whether it is the culprit or not. If so, replace your boiler’s faulty LWCO device. The other effective ways to get rid of these troubles are: 

  • Properly maintain your boiler regular intervals and correctly take care of it 
  • Ensure your boiler and LWCO device’s proper modification 
  • Replace the physically damaged LWCO, faulty plugged gauge glass, and lousy probe lead wire 
  • Make sure your boiler or LWCO device is not going through the short circuit 

2. Bad Ground

Your boiler’s circuit is not solidly grounded, or the ground is faulty, another reason for your Honeywell low water cut-off issue.

Using green wire or copper, the electrical panel grounded all the way to the boiler itself. 

The jacket’s sheet metal is considered an iffy or grounding circuit. However, your boiler’s LWCO keeps tripping due to the grounding circuit malfunction. The causes of it are: 

  • Loose, damaged, or rusted ground wires 
  • Poor component installation 
  • Damaged, loose, or corroded ground battery terminal 
  • Low alternate voltage output 
  • Heavy cranking 
  • Faulty wiring 


The ways to get rid of all these troubles mentioned above are: 

  • Replace the loose, damaged, and rusted ground battery terminal and wires and defective wiring 
  • Ensure the installation of high-quality component 
  • Make sure the voltage output is stable and high enough 

3. Boiler Require Skimming

In your running boiler, when the sight glass’s water bounces a lot or even drops in the glass’s bottom by an inch, it means your boiler requires skimming.

Lack of proper skimming is one of the main reasons why the low water cut-off wiring diagram keeps tripping. The boiler is more sensitive to oil in the water, so it requires skimming frequently. 


From your boiler’s sight glass, check whether it requires skimming or not. If the LWCO tripping issue is taking place due to the lack of skimming, you should do it immediately. Take time and very slowly skim your boiler multiple times and several hours. 

Do a real skim. Only the drain’s water draining is not a real skim. For a few minutes, run the boiler to heat the water. After heating the water properly, start the skimming. Some people also suggest that you can do skimming in cold water also. 

The oil is sitting on the boiler water’s surface and pressure the boiler water to wet returns by pushing it back. The boiler’s rear valve is located in the midway. And you should skim from the rear valve.

Remove the water surface’s oil or any other contamination. Finally, skimmed your boiler for several hours. 

4. Oils On The LWCO Probe

Oil on the LWCO probe is another reason why it is tripping. The LWCO device fails to operate or skim properly because of excessive oil on it. So it is another reason why the LWCO keeps tripping. 


Check the LWCO probe before starting the skimming. If too much oil accumulated on the probe, replace it immediately. 

5. Low Water Condition

The low water cut-off protects your boiler or prevents the boiler’s catastrophic failure. Thus the boiler’s low water condition is one of the main reasons why you require the low water cut-off troubleshooting guide.

Even when the boiler sensor is working, the LWCO trips due to the low water condition. The cause of it is: 

  • Feedwater pump failure 
  • Loss of water to the makeup water system 
  • Failed control valve 
  • Feedwater storage in the feed tank 
  • Feedwater’s accidental isolation 
  • Safety valve lifting 


The boiler’s low water condition means the water level is lower than the lowest permissible level.

Check your boiler’s surrounding piping to see whether the low water condition is creating the tripping issue or not.  The other solutions are: 

  • Replace the failed Feedwater pump and lousy control valve
  • Ensure there is no water loss in the make-up water system 
  • Make sure the Feedwater is not isolated 
  • Prevent the safety valve’s lifting

6. Water-Logged Float

A float will naturally sink when it gets water-logged. The water-logged float causes the tripping of LWCO. This failure is easily detectable.

When the operators following the switching mechanism bypass the boiler’s electrical connectors, it eliminates LWCO protection. The elimination of protection results in LWCO tripping. 


Following the switching mechanism, avoid doing the electrical connector’s bypass. If you don’t bypass the electrical connectors, the LWCO protection will remain the same. And it will not trip also. 

7. Faulty Sensor

The boiler’s temperature sensor helps to maintain a specific temperature level for reliable, safe, and efficient operation.

The water detection sensor immediately detects the water leak’s presence. And the pressure sensor monitors and tracks the boiler’s output pressure. 

Now, if any of these sensors go wrong, the boiler fails to operate properly, and it causes the tripping of LWCO. The factors responsible for these sensor’s malfunction are: 

  • Steam exposure 
  • Not well-optimized plumbing set-up
  • Damaged or disconnected sensor 
  • Overheating boiler 


Due to the sensor malfunction, your boiler’s water may remain cold or overheat, or the boiler may have insufficient water.

All these situations hinder the LWCO’s general functioning process and it keeps tripping. The ways to fix all these above troubles are: 

  • Avoid excessive steam exposure 
  • Ensure your boiler’s plumbing set is well optimized 
  • Replace the damaged or disconnected sensor 
  • Make sure your boiler is heating and functioning perfectly 


How does a boiler low water cut-off work?

The low water cut-off detects your boiler’s low water condition, and it turns down the boiler. This device keeps the burner off as long as the water doesn’t return. Once water returns, the burner starts to fire normally. 

What is the suitable boiler water temperature when draining a boiler?

Under 140 degrees Fahrenheit, the temperature is suitable for draining a boiler. Once the temperature is less than 140 degrees and the gauge pressure PSI is zero. Then open the boiler drain and air vent for emptying the boiler. 

Is a low water cut-off required?

Yes! Irrespective of the size of the steam heating boiler, it requires a low water cut-off device. Also, where the boilers are installed is not a matter at all. 


We break down each factor’s A-Z details causes and solutions in this article. And optimistically, you now know why your low water cut-off keeps tripping. If for any of the above reasons, your LWCO starts tripping, you will now fix it by yourself in no time. 

However, comment on your trouble if you face any other problems except the above. We’ll help you with easy solutions. 

About William

William is the founder of Fireplacehubs.com. He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

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